For about 99% of HU's, no. There were some built by Pioneer a few years back that could bridge the rear channels to a single sub. The bridged rear channels were probably good for 50w at most.
Grab yourself an inexpensive 4ch amp. You can get something decent off ebay for $50 or so. Pick up a 4ch amp install kit from
www.knukonceptz.com to install it.
